In recent years, almost all aircraft fuel tanks are so-called integral tanks such as those described in Patent Literature 1, wherein the airframe structure itself forms a portion of the tank container. In one example of an integral tank, the region enclosed by the front spar, the rear spar, and the upper and lower wing panels, which represent sections of the main wing, is used as a tank. In other words, these airframe structures are used as a container for storing fuel.
Pipes such as a fuel pipe for supplying fuel and an inert gas pipe for supplying an inert gas are installed inside this tank.
On the other hand, materials that are lightweight, high-strength and provide good durability are in demand for the airframe materials such as the main wing of the aircraft, and for example, light metal materials such as aluminum alloys are widely used.
In recent years, as these demands have grown stronger, the use of resin materials that have been reinforced with fiber (composite materials) as airframe materials is becoming more widespread.
For example, carbon fiber reinforced plastics (CFRP) prepared by immobilizing carbon fibers within an epoxy resin or the like are widely used as these composite materials.